Such a manometer is known from DE 101 23 103 A1. This has a housing with a bourdon tube arranged therein, a connecting piece rigidly connected to the housing, a viewing glass arranged on the housing, and a pointer that can rotate at the bottom side of the viewing glass. The pointer is in engagement with the free end of the bourdon tube. The connecting piece of this known manometer has threads on its outer side. The manometer is fixed, e.g., in a fire extinguisher valve, by means of these threads. The screwing on and tightening of the manometer is typically realized by means of a hexagonal head, which is provided on the outer side of the connecting piece. By means of a commercially available wrench, the manometer can then be fixed by hand. However, this type of mounting has the disadvantage that automatic assembly is not possible without additional means.